Kinetics of the proton-deuteron exchange at position H8 of adenine and guanine in DNA.

AUTOR(ES)

Brandes, R

RESUMO

Proton-NMR has been used to determine the activation energies and pre-exponential factors for the deuterium exchange of AH8 in poly(dA-dT).poly(dA-dT), and for GH8 in poly(dG-dC).poly(dG-dC). No simple relationship between the kinetic parameters and molecular conformation was found. By addition of 4.5 M NaCl a transition from the B to the Z conformation was induced for poly(dG-dC).poly(dG-dC), and an increased exchange rate was observed. The exchange rate for poly(dA-dT).poly(dA-dT) also increased below 64 degrees C, and a significant decrease in activation energy on addition of 4.5 M NaCl was observed. The exchange rates at T = 55.8 degrees C were also measured for the AH8 and GH8 in random sequence calf thymus DNA. From the difference in exchange rates, a method of preferential labeling of either the AH8 or the GH8 in high molecular weight DNA is evaluated.

Documentos Relacionados

• Selective alkylation of carcinogenic 9-anthryloxirane at the N-3 position of adenine in DNA.
• Dimerization of the guanine-adenine repeat strands of DNA.
• N-Sulfomethylation of guanine, adenine and cytosine with formaldehyde-bisulfite. A selective modification of guanine in DNA.
• A kinetic study of 1H leads to 3H exchange in C(8) H-groups of purinic residues in DNA.
• Exchange kinetics of the Schiff base proton in bacteriorhodopsin.